The present invention relates to the area of cold air inflatable structures and systems including creation of large items such as enclosures and structures such as tent-like and tunnel inflatables. In particular, the present invention is directed toward an inflatable structure having interior and exterior fabric walls tied together with mesh or cords.
In the present Specification, the term xe2x80x9ccold air inflatable systemxe2x80x9d is used to distinguish between hot air inflatable structures (e.g., hot air balloons) and cold air inflatable structures (e.g., tents, domes, and other structures) which use air pressure (e.g., fan) to inflate and maintain shape. Cold air inflatable systems are generally inflated by the injection of cold air introduced through a low pressure high volume fan (e.g., forward curve xe2x80x9csquirrel cagexe2x80x9d type fan).
Inflatable structures are known in the art. Typical cold air inflatable products are usually manufactured from PVC (polyvinyl chloride), nylon, and similar materials and may be shaped into a multiplicity of designs and sizes. However, Prior Art construction techniques have limited some design aspects of inflatable structures.
One of the most commonly known inflatable structures is the inflatable dome, such as used for athletic arenas or facilities (e.g., Carrier Dome, Syracuse N.Y.). In a stadium embodiment, a large fabric dome may be attached to the stadium which in turn is pressurized to support the dome into a convex shape. In smaller applications (e.g., tennis enclosure) the dome material may be attached directly to the ground and the entire structure inflated.
An example of an inflatable arena dome is illustrated, for example, in Simens, U.S. Pat. No. 6,282,842, issued Sep. 4, 2001, and incorporated herein by reference. Simens discloses a sports stadium or building complex covered by a huge fiberglass fabric dome supported by an inflatable dual-membrane bladder on a hollow compression ring with a diameter of 800 to 1200 feet. A central vertical spreader having upper and lower tension rings connected to the membranes of the bladder is supported from above or below by separate suspension cables in a position above the compression ring. Containment cables limit the expansion of and shape the bladder to provide a closed pressurized air space of narrow lenticular cross section and can include 40 or more radial ceiling cables and the same number of radial hold-down cables of the same length.
One problem with such systems is that they require that the interior of the structure be maintained at a pressure higher than the surrounding atmospheric pressure. Thus, at each entrance, an airlock need be provided in the form of a revolving door or the like. Rapid ingress and egress is not readily achieved, and large open areas (i.e., open to the elements) are not possible. Moreover, such structures are not readily portable, as they must be attached and sealed against a structure or the ground. Thus, such designs are generally unsuitable for tents, pavilions, and the like, where large entryways and openings are desired and portability is a requirement.
Other types of inflatable structures are known in the art such as jumping castles, product replicas, billboards, and the like. Most of these products are merely inflatable envelopes which are pressurized by a small fan. Jumping castles, however, may be formed as structure having an internal cavity for users to enter.
In such an embodiment, walls and structure may be formed by joining inner and outer panels together (or via an intermediate strip) to form a series of inflatable adjoining xe2x80x9ctubesxe2x80x9d. The difference in pressure between the inside of the inflatable and the outside provides sufficient surface tension for the device to have sufficient rigidity to maintain its shape.
An example of such a tube construction is illustrated, for example, in Peacock et al., U.S. Pat. No. 5,893,238, issued Apr. 13, 1999, and incorporated herein by reference. Peacock discloses an inflatable tent construction including an upper wall unit and a lower wall unit having a plurality of vertically aligned inflatable tubular chambers wherein the lower wall unit is operatively connected to a floor unit and provided with a plurality of tent opening units. A plurality of inflatable circular rings encircle the periphery of the floor unit, the lower wall unit, and the upper wall unit, respectively.
While such a structure may maintain a desired shape and appearance, the use of this tube-type assembly makes the structure fairly heavy and complex. As a result, such inflatable technology does not scale well into larger structures such as large tents and the like.
Traditional construction of many inflatable products has required the use of an inner and outer wall separated by a series of internal walls or baffles of similar materials to the main walls in order to give the device being manufactured sufficient strength and stability. However, such construction adds significantly to the weight of the inner and outer walls along and can contribute up to a 40% increase in the total weight of the an inflatable device. Moreover, the addition of internal walls or baffles increases the deflated size of the structure, making the structure harder to store and ship. In addition, such inflatable devices are slow to inflate and deflate, as considerable time is needed to fill each xe2x80x9ctubexe2x80x9d or cavity in the structure.
Attempts have been made to overcome the defects of such Prior Art structures. One example of such a structure may be found in Charbonneau, U.S. Pat. No. 4,932,169, issued Jun. 12, 1990 and incorporated herein by reference. Charbonneau discloses a rather elaborate inflatable structure comprising a double wall pneumatic envelope including top and bottom panels. The inflatable structure also includes a central mast and a series of peripheral poles. A central portion of the bottom panel is mounted to a top end of the mast, whereas the bottom end of the mast is secured to the ground. The poles are connected at their upper and lower ends respectively to peripheral portions of the envelope and to the ground. However, the addition of the central and peripheral poles makes setting up the structure time consuming and moreover increases the bulk of the structure when folded and packed for shipping or storage.
It is an object of the present invention to provide a means of producing an inflatable object which results in a lighter weight product than previous such objects and which is more efficiently inflated and deflated.
In one embodiment of the present invention, a method of constructing an inflatable object includes the steps of providing attachment points to opposing interior faces of the object and connecting these attachment points by means of predetermined lengths of connection material prior to inflation.
The invention also includes an inflatable device formed by the above method and having opposing walls having interior faces which include attachment points adapted to be connected together by predetermined lengths of material, the arrangement being such that upon inflation of the device, the walls are held in position relative to one another by the lengths of material.
It is preferred that the connection material between the inner and outer panels be a cord-like material and it is also preferred that the material used may be flexible. However any appropriate material may be used. It is further preferred that the attachment points be located on base members attached to the interior face of each wall and that the attachment points take the form of eyelets.